[0001] The present invention relates to a clutch motor arrangement including an electric
motor equipped with a fly wheel mounted on a motor output shaft of the electric motor
and a clutch mechanism movably supported so as to reciprocate in an axial direction
of said electric motor for selective contact with and spacing from said fly wheel
through operation of a clutch operating lever so as to intermittently transmit torque
of the electric motor to a clutch output shaft of said clutch mechanism by operating
said clutch operating lever.
[0002] Commonly, in the sewing machines particularly for industrial purposes, very fast
rising speeds and frequent on/off functionings or inching function are required and
therefore, clutch motors employed for driving such sewing machines have considerably
large power consumption, since fly wheels with a large moment of inertia are rotated
at a speed close to the synchronous speed at all times, while the full power source
voltage is applied to the motor even during a non-load period in which the sewing
machines are not driven. Especially, in a single-phase clutch motor which occupies
the majority of clutch motors, the power consumption as described above is particularly
large owing to the characteristics inherent in the single-phase induction motors.
[0003] Since the actual sewing period of industrial sewing machines is less than 30% of
the total working period, the clutch motor is undesirably subjected to the non-load
operation for more than 70% of the working period and so a large amount of power is
wasted.
[0004] Conventionally, no particular countermeasures have been conceived for reduction of
the power consumption during the non-load period as described above, and even if any
measure is adopted, such a countermeasure has been limited only to some consideration
taken during the designing of the motor main body in order to decrease the non-load
loss of the motor even to a slight extent. It is an object of the present invention
to provide a clutch motor arrangement especially for use in industrial sewing machines
and the like, which has exactly the same performance as in the conventional clutch
motors, with only the power consumption being reduced for saving, in which vibrations
and noises of the motor are suppressed during shut-down of for instance a sewing machine,
which is readily applicable to any existing clutch motor for the reduction of power
consumption, which is provided with a detection device of non-contact type to detect
functioning of a clutch mechanism for positive operation without being affected by
side plays arising from abrasions and dimensional tolerances of each part of the clutch
motor, and giving no adverse effect to the functioning of a clutch lever and which
is simple in construction and stable in functioning, and be readily incorporated into
industrial sewing machines of various type at low cost.
[0005] In accomplishing these objects according to the present invention the clutch motor
arrangement further comprises a control device for controlling voltage to be applied
to the electric motor, and a detection device for detecting functioning of said clutch
mechanism, said clutch motor arrangement and said detection device being arranged
such that in response to output signals of the detection device, full supply voltage
is applied to the electric motor during the operative "IN" state of the clutch mechanism
and a voltage lower than the full supply voltage is applied during the operative "OFF"
state of said clutch mechanism.
[0006] By the arrangement of the present invention as described above, an improved clutch
motor arrangement for use in industrial sewing machines and the like has been advantageously
presented at a reduced power consumption, with suppressed vibrations and noises during
shutdown of the motor, and substantial elimination of disadvantages inherent in the
conventional clutch motor arrangements of this kind.
[0007] These and other objects and features of the present invention will become apparent
from the following description taken in conjunction with the preferred embodiment
thereof with reference to the accompanying drawings, in which;
Fig. 1 is a side elevational view, partly broken away, of a conventional clutch motor
arrangement.
Fig. 2 is a graph explanatory of the principle of a clutch motor arrangement according
to the present invention,
Fig. 3 is a block diagram showing the construction of a clutch motor arrangement according
to one preferred embodiment of the present invention,
Figs. 4 through 7 are diagrams and graphs explanatory of the functions of the clutch
motor arrangement of Fig. 3,
Fig. 8 is a side elevational view of the clutch motor arrangement according to the
present invention particularly showing the structure of a detection device employed
therein,
Fig. 9 is a fragmentary side sectional view showing, on an enlarged scale, the structure
of the detection device employed in the arrangement of Fig. 8,
Fig. 10 is a fragmentary side elevational view showing, on an enlarged scale and partly
in section, the clutch operating lever employed in the arrangement of Fig. 3 for explaining
the function thereof,
Figs. 11 to 13 are diagrams explanatory of the functioning of the clutch operating
lever of Fig. 10, and
Fig. 14 is a view similar to Fig. 10, which particularly shows adjustment of a support
plate employed therefor.
[0008] Before the description of the present invention proceeds, it is to be noted that
like parts are designated by like reference numerals throughout several views of the
accompanying drawings.
[0009] Referring now to the drawings, there is shown in Fig. 1 a conventional clutch motor
arrangement which generally includes a clutch motor M having a frame 1, a bracket
2, a stator 3, a rotor 4 and a motor output shaft 5, a fly wheel 6 mounted on the
motor output shaft 5, a clutch disc 8 on which a clutch friction material 7 to be
engaged with the fly wheel 6 is mounted, a brake base 10 on which a brake friction
material 9 is mounted, a brake adjusting bolt 11 for adjusting the brake, a clutch
output shaft 12 to which the clutch disc 8 is secured, ball bearings 13 and 14 respectively
provided in a cylinder 15 at the side remote from a load and at the load side for
rotatably supporting the clutch output shaft 12, a clutch bracket 16 having a cylindrical
portion 17 for movably supporting therein the cylinder 15 for reciprocation in the
axial direction, a pin 18 fitted in the cylinder 15, a clutch operating lever 19 for
operating the clutch, and a shaft 20 for pivotally supporting said clutch operating
lever 19.
[0010] In the above known arrangement, during sewing operation, the clutch motor M equipped
with the fly wheel 6 is normally rotating, and the clutch disc 8 secured to the clutch
output shaft 12 is arranged to axially move between the fly wheel 6 and brake friction
plate 9 through the pin 18, cylinder 15, and ball bearings 13 and 14 for external
transmission of the motor torque and brake operation.
[0011] Generally, a clutch motor, for example, of a single phase 200 W type has such a power
consumption that, when an industrial sewing machine is driven at the rated output
of 200 W, the motor requires an input of approximately 300 W, and even when the sewing
machine is not being driven, an input of approximately 100 W is required for operating
the motor under a non-load condition. On the assumption that the actual working period
of the industrial sewing machine is 30% as stated earlier, the average power consumption
of the above clutch motor of the single phase 200 W type is represented by,
(300Wx30+100Wx70)=100=160W
[0012] In the conventional arrangements, reduction of the power consumption is intended
to be achieved by a decrease of the input during the loading period through improvement
of the efficiency of the motor, and also by a decrease of the input during the non-load
period, and thus, it has been difficult to achieve a large effect thereby.
[0013] On the contrary, the present invention is based on the principle to lower the voltage
to be impressed to the motor during the non-load period of the motor for reduction
of power consumption at such non-load period.
[0014] Commonly, in a clutch motor, it is necessary to keep the fly wheel rotating at a
speed close to the synchronous speed even during the non-load period. However, as
shown in Fig. 2, if the voltage to be applied to the motor is lowered, although the
torque of the motor is reduced, with a S-T or speed-torque curve varying from the
state represented by a curve A to that shown by a curve B in Fig. 2, since the load
at the non-load period is very small and limited only to windage loss, mechanical
loss at bearings, etc., the load curve takes the form as shown, with merely a slight
reduction of the motor revolutions during the non-load operation from S
OA to S
¿µ, thus inviting substantially no problem during actual use.
[0015] Accordingly, for example, if the voltage to be applied to the motor during the non-load
period of the clutch motor of the single phase 200 W type is reduced from 100 V to
50 V, the input at the non-load period becomes approximately 25 W, and therefore,
the average power consumption for the clutch motor is represented by, (300 W x 30
+ 25 W x 70) - 100 = 109 W which is a reduction of the power consumption as far as
approximately 30% as compared with the conventional arrangements.
[0016] Referring now to Fig. 3, there is shown a clutch motor arrangement according to one
preferred embodiment of the present invention which is applied to a clutch motor of
a single phase type. The clutch motor arrangement of Fig. 3 generally includes a clutch
motor 21, a bi-directional three-terminal thyristor 22 connected in series with the
motor 21, a detection divide 23 so provided as to detect the positions of a clutch
operating lever 19A, and a control circuit 24 inserted between the detection device
23 and the thyristor 22 for transmitting predetermined gate signals to the thyristor
22 through corresponding signals from the detection device 23.
[0017] It should be noted here that other constructions of the clutch motor arrangement
of Fig. 3 are generally similar to those of Fig. 1, and therefore, detailed description
thereof is abbreviated here for brevity.
[0018] Referring also to a diagram of Fig. 4 showing the relation between the positions
of the operating lever 19A and the voltages to be applied to the motor 21 for explaining
the functioning of the arrangement of Fig. 3, when the operating lever 19A is in the
inoperative OFF position, a gate signal for effecting a preliminarily set phase control
is transmitted from the control circuit 24 to the bi-directional three-terminal thyristor
22, whereby a predetermined voltage lower than the power source voltage is impressed
to the motor 21. Upon changing over of the positions of the operating lever 19A from
the inoperative OFF position to the operative ON position, the above state is detected
by the detection device 23, and thus, a gate signal for full conduction of the thyristor
22 is instantly transmitted to the bi-directional three-terminal thyristor 22 from
the control circuit 24, while the full power source voltage is applied as it is to
the motor 21. Meanwhile, when the positions of the operating lever 19A have been changed
over from the operative ON position to the inoperative OFF position, the state is
detected by the detection device 23, while the gate signal for effecting the preliminarily
set phase control is fed to the thyristor 22 from the control circuit 24 at a predetermined
time delay of to second, and the functionings as described in the foregoing are repeated
henceforth.
[0019] When the positions of the operating lever 19A are changed over from the ON position
to the OFF position, if the change-over from the full conduction to the phase control
is momentarily effected, the S-T curves instantly change from the curve A to curve
B as shown in Fig. 5, and since it is necessary to accelerate the revolutions of the
motor rendered to the SI due to application of the load, up to S
OB through a small torque, a considerably long period of time is required for the purpose.
[0020] However, if the full conduction is maintained after the predetermined time delay
of to second, even upon change-over of the positions of the operating lever 19A from
the ON position to the OFF position, the revolutions of the motor rendered to be SI
due to the application of the load are accelerated up to a large torque S
OA' and thus, it is possible to return to S
OB in a short period of time.
[0021] It should be noted here that in the absence of the delay function as described above,
the functioning can not catch up with the inching operation in which the positions
of the operating lever 19A are rapidly changed over in such a manner as in a successive
change-over through ON, OFF, ON and OFF positions.
[0022] However, by the delayed functionings provided in the present invention as described
earlier, since the full voltage is continuously applied to the motor even during the
inching operation in which the time t for the OFF period is shorter than the delayed
time to, the clutch motor can be provided with a sufficient torque as shown in Fig.
7.
[0023] Reference is made to Figs. 8 and 9 showing the detailed structure of the detection
device 23 employed in the clutch motor arrangement of the present invention referred
to in Fig. 3.
[0024] The detection device 23 for detecting whether the operating lever 19A is in the inoperative
OFF position or in the operative ON position, generally includes a support plate 26
having an elongated opening 26a defined therein and movably fitted in a guide groove
27 (Fig. 14) formed in the operating lever 19A for guiding the support plate 26 to
any position on an arcuate path about the pivotal axis 20A of the lever 19A, a fixing
screw 28 threaded into the lever 19A through the elongated opening 26a of the support
plate 26 for fixing said support plate 26 at any desired position in the guide groove
27, a magnetic shielding plate 25 integrally formed with or rigidly connected to the
support plate 26 so as to extend upwardly from one end of said support plate 26, permanent
magnet member 29 fixedly provided on a frame (not shown) or the like of the clutch
motor arrangement in a position adjacent to one side of the magnetic shielding plate
25, and a magnetic sensing element, for example, of a lead switch 30 also fixedly
provided on a frame (not shown) or the like of the clutch motor arrangement in a position
adjacent to the other side of the magnetic shielding plate 25 so as to confront the
permanent magnet member 29 through said support plate 26 and magnetic shielding plate
25.
[0025] In the above arrangement, as shown by the chain line in Fig. 10, when the operating
lever 19A is in the OFF position, the magnetic shielding plate 25 which has been moved
upwardly together with the support plate 26 is spaced from the magnet member 29, and
thus, the lead switch 30 which is not shielded from magnetic flux of the permanent
magnet member 29 is in the turned-on state. Meanwhile, as shown by the solid line
in Fig. 10, when the operating lever 19A is brought to the ON position, the magnetic
shielding plate 25 is lowered between the magnet member 29 and lead switch 30 so as
to shield said lead switch 30 from magnetic flux of the magnet member 29, and thus,
the lead switch 30 is turned off. In other words, the central circuit 24 connected
between the lead switch 30 and the thyristor 22 is capable of judging whether the
operating lever 19a is in the OFF position or in the ON position.
[0026] Initially, when the operating lever 19A is moved from the OFF position to the ON
position, the magnetic shielding plate 25 is displaced from the point A to point B
on a concentric arcuate path about the center 0 of the pivotal axis 20A as shown in
Fig. 11. Meanwhile, as shown in Fig. 12, upon abrasion of the brake friction material
9 (Fig. 1), the OFF position of the operating lever 19A is displaced from the point
A to point C, while upon wearing of the clutch friction material 7 (Fig. 1), the ON
position of the control lever 19A is moved from the point B to point D, and when the
operating lever 19A is changed over from the OFF position to the ON position, the
magnetic shielding plate 25 is to be displaced from the point C to point D along the
concentric arcuate path about the center O of the pivotal axis 20A.
[0027] However, according to the present invention, even when the brake friction material
9 and clutch friction material 7 are abraded, it is possible to detect the OFF and
ON positions of the operating lever 19A as in the original state only by making the
length L (Fig. 10) of the magnetic shielding plate 25 longer than the maximum variation
amount I of the operating point due to abrasion of the clutch friction material 7
as shown in Fig. 12. Furthermore, although the operation of the lever 19A may become
rather difficult if the moving distance of said lever 19A is increased from the points
A to B to the points C to D, by adjusting the position of the brake friction material
9 with the brake adjusting bolt 11 (Fig. 1), the moving distance of the operating
lever 19A may be reduced to the points B to D as shown in Fig. 13. In the above case,
although the functioning point of the operating lever position detection device may
be varied, this is corrected merely by moving the support plate 26 along the guide
groove 27 as shown in Fig. 14, and thus, according to the present invention, the correction
and maintenance of the operating lever position detection device are very readily
effected by the brake adjusting bolt 11.
[0028] It should be noted here that, in the above embodiment, although the present invention
is mainly described with reference to the single phase motor, the present invention
is not limited in its application to the single phase motor alone, but may readily
be applicable to three-phase motors and the like based on the same principle as described
in the foregoing.
[0029] Although the present invention has been fully described by way of example with reference
to the attached drawings, it is to be noted that various changes and modifications
will be apparent to those skilled in the art. Therefore, unless otherwise such changes
and modifications depart from the scope of the present invention, they should be construed
as included therein.
1. A clutch motor arrangement (21-24) including an electric motor (21) equipped with
a fly wheel (6) mounted on a motor output shaft (5) of the electric motor (21) and
a clutch mechanism movably supported so as to reciprocate in an axial direction of
said electric motor (21) for selective contact with and spacing from said fly wheel
(6) through operation of a clutch operating lever (19, 19A) so as to intermittently
transmit torque of the electric motor (21) to a clutch output shaft (12) of said clutch
mechanism by operating said clutch operating lever (19, 19A), characterized in that
said clutch motor arrangement (21-24) further comprises a control device (24) for
controlling voltage to be applied to the electric motor (21 ), and a detection device
(23) for detecting functioning of said clutch mechanism, said clutch motor arrangement
(21-24) and said detection device (23) being arranged such that in response to output
signals of the detection device (23), full supply voltage is applied to the electric
motor (21) during the operative "IN" state of the clutch mechanism and a voltage lower
than the full supply voltage is applied during the operative "OFF" state of said clutch
mechanism.
2. A clutch motor arrangement as claimed in claim 1, characterized in that said control
device (24) further includes a thyristor element (22) connected in series with said
electric motor (21) and a control circuit for controlling conduction angle of said
thyristor element (22) so that, by output signal of the detection device (23) which
detects positions of the clutch operating lever (19A), the thyristor element (22)
is rendered to be fully conductive so as to apply the full power source voltage to
said electric motor (21) when said clutch operating lever (19A) is in the operative
IN position, and said thyristor element (22) is subjected to phase control so as to
apply part of the full power source voltage to said electric motor (21) when said
clutch operating lever (19A) is in the inoperative OFF position.
3. A clutch motor arrangement as claimed in claim 1, characterized in that said thyristor
element (22) is a thyristor of inverted parallel connection.
4. A clutch motor arrangement as claimed in claim 1, characterized in that said thyristor
element (22) is a bi-directional three-terminal thyristor.
5. A clutch motor arrangement as claimed in claim 1 or claim 2, characterized in that
the thyristor element (22) of said control device (23) is arranged to be instantly
changed over from the state subjected to the phase control to the fully conductive
state upon changing over of the positions of said clutch operating lever (1 9A) from
the inoperative OFF position to the operative ON position, and also to be changed
over, through a predetermined period of time delay, from said fully conductive state
to said state subjected to the phase control upon changing over of the positions of
said clutch operating lever (19A) from said operative ON position to said inoperative
OFF position.
6. A clutch motor arrangement as claimed in claim 1, characterized in that said detection
device (23) further comprises a magnet member (29) and a magnetic sensing element
(30) disposed to confront each other, and a magnetic shielding plate (25) arranged
to be movable in a space between said magnet member (29) and said magnetic sensing
element (30).
7. A clutch motor arrangement as claimed in claim 6, characterized in that said magnetic
shielding plate (25) is movably disposed in a guide groove (27) formed in said clutch
operating lever (19A).
8. A clutch motor arrangement as claimed in claim 7, characterized in that said guide
groove (27) is so formed as to guide said magnetic shielding plate (25) to any desired
position on an arcuate path centered at a pivotal axis (20A) supporting said clutch
operating lever (19A).
1. Kupplungsmotoranordnung (21-24) mit einem Elektromotor (21), der mit einem auf
einer Motor-Ausgangswelle (5) des elektrischen Motors (21) befestigten Schwungrad
(6) versehen ist, und einem beweglich gelagerten und in axialer Richtung des elektrischen
Motors (21) hin- und herbewegbaren Kupplungsmechanismus, der durch Betätigung eines
Kupplungs-Betätigungshebels (19, 19A) selektiv mit dem Schwungrad (6) kontaktiert
und vom Schwungrad (6) getrennt wird, um das vom elektrischen Motor (21) abgegebene
Drehmoment zur Kupplungs-Ausgangswelle (12) des Kupplungsmechanismus' durch Beätigung
des Kupplungs-Betätigungshebels (19, 19A) zu übertragen, dadurch gekennzeichnet, daß
die Kupplungsmotoranordnung (21-24) zusätzlich eine Steuervorrichtung (24) zur Steuerung
der an den elektrischen Motor (21) angelegten Spannung und eine Erfassungsvorrichtung
(23) zur Erfassung der Funktion des Kupplungsmechanismus' aufweist, wobei die Kupplungsmotoranordnung
(21-24) und die Erfassungsvorrichtung (23) so angeordnet sind, daß mit den Ausgangssignalen
der Erfassungsvorrichtung (23) die volle Versorgungsspannung während des wirksamen
"EIN"-Zustandes des Kupplungsmechanismus' an den elektrischen Motor (21) und während
des wirksamen "AUS"-Zustandes des Kupplungsmechanismus' eine Spannung, die niedriger
als die volle Versrogungsspannung ist, angelegt wird.
2. Kupplungsmotoranordnung nach Anspruch 1, dadurch gekennzeichnet, daß die Steuervorrichtung
(24) ein in Reihe zum elektrischen Motor (21) geschaltetes Thyristorelement (22) und
eine Steuerschaltung zur Steuerung der Stromflußdauer des Thyristorelements (22) enthält,
wobei das Ausgangssignals der die Stellung des Kupplungsbetätigungshebels (19A) erfassenden
Erfassungsvorrichtung (23) das Thyristorelement (22) voll leitfähig hält, um die volle
Versorgungsspannung an den elektrischen Motor (21) zu legen, wenn der Kupplungsbetätigungshebel
(19A) sich in der wirksamen Einschaltstellung befindet und das Thyristorelement (22)
der Phasensteuerung unterworfen wird, um einen Teil der vollen Versorgungsspannung
an den elektrischen Motor (21) zu legen, wenn der Kupplungsbetätigungshebel (19A)
sich in der unwirksamen Ausschaltstellung befindet.
3. Kupplungsmotoranordnung nach Anspruch 1, dadurch gekennzeichnet, daß das Thyristorelement
(22) aus parallel und in entgegengesetzter Durchlaßrichtung geschalteten Thyristoren
besteht.
4. Kupplungsmotoranordnung nach Anspruch 1, dadurch gekennzeichnet, daß das Thyristorelement
(22) aus einem bidirektionalen Thyristor mit drei Anschlüssen besteht.
5. Kupplungsmotoranordnung nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß das
Thyristorelement (22) der Steuervorrichtung (23) augenblicklich vom Zustand der Phasensteuerung
in den voll leitfähigen Zustand bei einem Stellungswechsel des Kupplungsbetätigungshebels
(19A) von der unwirksamen Ausschaltstellung in die wirksame Einschaltstellung und
nach einer vorbestimmten Zeitverzögerung von dem voll leitfähigen Zustand in den Phasensteuerzustand
bei einem Stellungswechsel des Kupplungsbetätigungshebels (19A) von der wirksamen
Einschaltstellung in die unwirksame Ausschaltstellung wechselt.
6. Kupplungsmotoranordnung nach Anspruch 1, dadurch gekennzeichnet, daß die Erfassungsvorrichtung
(23) einen Magneten (29) und ein magnetisches Abtastelement (30), die einander gegenüberliegend
angeordnet sind, sowie eine magnetische Abschirmplatte (25) enthält, die in dem Zwischenraum
zwischen dem Magneten (29) und dem magnetischen Abtastelement (30) beweglich angeordnet
ist.
7. Kupplungsmotoranordnung nach Anspruch 6, dadurch gekennzeichnet, daß die magnetische
Abschirmplatte (25) in einer in den Kupplungsbetätigungshebel (19A) eingeformten Führungsnut
beweglich angeordnet ist.
8. Kupplungsmotoranordnung nach Anspruch 7, dadurch gekennzeichnet, daß die Führungsnut
(27) so ausgebildet ist, daß sie die magnetische Abschirmplatte (25) auf einem bogenförmigen
Weg, dessen Zentrum auf der Drehachse (20A) des Kupplungsbetätigungshebels (19A) liegt,
in jede gewünschte Lage bringt.
1. Agencement de moteur à embrayage (21-24) comprenant un moteur électrique (21) équipé
d'un volant (6) monté sur un arbre de sortie (5) du moteur électrique (21) et un mécanisme
d'embrayage supporté de manière mobile de façon à être animé d'un mouvement de va-et-vient
dans une direction axiale du moteur électrique (21) pour venir sélectivement en contact
avec le volant et s'en éloigner, grâce au fonctionnement d'un levier d'actionnement
d'embrayage (19, 19A) de façon à transmettre par intermittence le couple du moteur
électrique (21) à un arbre de sortie (12) du mécanisme d'embrayage par actionnement
du levier (19, 19A), caractérisé en ce qu'il comprend en outre un dispositif (24)
de commande de la tension à appliquer au moteur électrique (21), et un dispositif
de détection (23) pour détecter le fonctionnement du mécanisme d'embrayage, cet agencement
(21-24) et le dispositif de détection (23) étant disposés de façon qu'en réponse à
des signaux de sortie du dispositif de détection (23), la pleine tension d'alimentation
soit appliquée au moteur électrique (21) pendant l'état de "marche" du mécanisme d'embrayage
et une tension inférieure à la pleine tension d'alimentation soit appliquée pendant
l'état d"'arrêt" du médcanisme d'embrayage.
2. Agencement selon la revendication 1, caractérisé en ce que le dispositif de commande
(24) comprend en outre un élément de thyristor (22) relié en série au moteur électrique
(21) et un circuit de commande de l'angle de conduction de l'élément de thyristor
(22) de façon que, en sortant un signal du dispositif de détection (23) qui détecte
les positions du levier d'actionnement d'embrayage (19A), l'élément de thyristor (22)
soit rendu totalement conducteur de manière à appliquer la pleine tension de la source
d'alimentation au moteur électrique (21) lorsque le levier d'actionnement d'embrayage
(19A) se trouve dans la position "marche", et l'élément de thyristor (22) soit soumis
à une commande de phase de manière à appliquer une partie de la pleine tension de
la source d'alimentation au moteur électrique (21) lorsque le levier d'actionnement
d'embrayage (19A) se trouve dans la position "arrêt".
3. Agencement selon la revendication 1, caractérisé en ce que l'élément de thyristor
(22) est un thyristor à connexion parallèle inversée.
4. Agencement selon la revendication 1, caractérisé en ce que l'élément de thyristor
(22) est un thyristor à trois bornes bidirectionnel.
5. Agencement selon la revendication 1 ou la revendication 2, caractérisé en ce que
l'élément de thyristor (22) du dispositif de commande (23) est disposé de manière
à passer instantanément de l'état où il y a soumission à une commande de phase à l'état
totalement conducteur lors du passage du levier d'actionnement d'embrayage (19A) de
la position "arrêt" à la position, "marche", et aussi de manière à passer, par l'intermédiaire
d'un retard de durée prédéterminée, de l'état de pleine conduction audit état de soumission
à la commande de phase lors du passage du levier d'actionnement d'embrayage (19A)
de la position "marche" à la position "arrêt".
6. Agencement selon la revendication 1, caractérisé en ce que le dispositif de détection
(23) comprend en outre un élément d'aimant (29) et un élément magnétique de détection
(30) disposés de façon à être en vis-à-vis, et une plaque de blindage magnétique (25)
disposée de manière à pouvoir de déplacer dans un espace situé entre l'élément d'aimant
(29) et l'élément magnétique de détection (30).
7. Agencement selon la revendication 6, caractérisé en ce que la pique de blindage
magnétique (25) est disposée de manière à pouvoir se déplacer dans une rainure de
guidage (27) pratiquée dans le levier d'actionnement d'embrayage (19A).
8. Agencement selon la revendication 7, caractérisé en ce que la rainure de guidage
(27) est formée de façon à guider la plaque de blindage magnétique (25) jusqu'à une
position désirée d'un trajet en forme d'arc autour de l'axe de pivotement (20A) supportant
le levier d'actionnement d'embrayage (19A).